The article popularly talks about widely used building materials, lightweight concrete, main characteristics and finishing methods using traditional technologies, plastering house elements.
Plastering aerated concrete walls
Plastering interior and exterior structures made of lightweight concrete is the most commonly used method of protecting against the effects of external climatic conditions and giving the house an original, respectable appearance, as well as internal comfort.
The prevalence of the technology is due to the ability to inexpensively and independently carry out a set of works on the preparation and finishing of structures and achieve the desired results.
Special characteristics of aerated concrete blocks
Aerated concrete refers to cellular concrete and consists of quicklime, cement, sand and gas-forming aluminum powder. When mixing components and water, a reaction occurs with the release of gas, forming voids, the number of which determines the weight, density, thermal conductivity of concrete and areas of use:
- Concrete with a density of 300-400 (kg/m3) is used for thermal insulation.
- Density 500-900 (kg/m3) allows it to be used for constructing partitions and walls.
- With a density of 1000-1200 kg/m3, concrete is used to make load-bearing walls.
Concrete has gained popularity in housing construction due to its properties:
- Low thermal conductivity allows it to be used as a heat-insulating substance.
- Frost resistance can reach 150 cycles; among lightweight concrete, only expanded clay concrete has greater durability.
- High fire resistance.
One of the negative qualities for construction is hygroscopicity, which means that aerated concrete needs a coating.
The hygroscopicity of aerated concrete requires isolation from moisture.
Preparing gas silicate blocks indoors for plastering
In aerated concrete the amount of cement is up to 60 percent, in gas silicate concrete no more than 14, lime is twice as much, the rest is sand. The percentage matters because the more cement, the higher the strength, and the base must be stronger than the coating, otherwise it will peel off. That is, the finishing of the house must be done with a lime-cement composition.
When finishing, you need to remember that the base must be stronger than the coating.
The main function of plastering surfaces made of gas silicate blocks is to form a vapor-impermeable barrier and limit moisture absorption. To improve the adhesion of the coating to the base, the structural elements are coated with a primer deep penetration, the first layer is applied generously, preferably with a spray gun, after drying it needs to be painted over again.
After priming, considering that gas silicate composition the base is weak, it is necessary to carry out reinforcement to prevent the appearance of cracks.
The rough layer of reinforcement is made from glue on which the blocks were laid, experienced craftsmen They use tile adhesive for this as a cheaper composition.
The use of glue instead of a conventional solution is associated with polymer additives in the composition, which ensure strong adhesion with a thin layer of the mixture.
After applying a thin layer of glue, 2-7 millimeters thick, a fiberglass mesh is embedded into it, which fixes the blocks and serves as a reliable base for the coating. The mesh is overlapped over the applied glue and pressed in with a notched spatula.
It is advisable to start applying the solution after 5-7 days, when reinforced layer will gain strength.
Plastering gas silicate blocks inside a building: technologies used
Protection of gas silicate structures occurs in three stages:
1.Plastering with lime-cement mortar.
2.Priming.
3. Putty.
A lime-cement or lime-gypsum mortar no more than one centimeter thick is applied to the reinforced surface.
The technology of manual plastering is common; if the wall is large and uneven, beacons are installed and the applied layer is leveled using a broad rule.
The solution is mixed in a bucket, small tank or trough, water is poured into the poured mixture and stirred to the required consistency, you need to cook a little, gypsum sets in 20 minutes, cement needs a little more time, so the amount should be sufficient to be processed during this time. You can level it immediately after laying it on; the last step is grouting.
After finishing, use a long strip to check the evenness of the surface; unevenness within 5-7 millimeters will not be noticeable.
Is it necessary to plaster the aerated concrete block from the outside?
The need to protect the façade made of aerated concrete is due to its properties:
- Hygroscopicity will lead to the saturation of gas blocks with water, which in frost will cause destruction of the structure.
- Mechanical impact will cause chips, dents, and cracks.
- The material has a porous structure with open pores through which circulating air carries away heat.
- Rough aerated concrete house looks unpresentable.
For aerated concrete structures, the danger is the accumulation of moisture inside the blocks, which freezes and destroys the block from the inside due to temperature changes. Therefore, the protection of external surfaces is mandatory; the plastering method of protection is widely used for various reasons, one of which is the low cost of this technology.
Materials used for exterior work
For application protective equipment externally, substances with the following qualities are needed:
- permeable to water vapor;
- not getting wet;
- with good grip;
- resistant to frost.
The main types of mixtures for finishing aerated concrete outside:
- Acrylic for aerated concrete, strengthens loaded structures, base.
- Silicate, include liquid glass;
- Silicone, based on silicon-organic polymers, is well suited for facades, but high in price;
- Gypsum mixture;
- Lime-cement composition.
Do-it-yourself internal plaster of aerated concrete block: features of the work
Due to the high hygroscopicity of the material, plastering inside the house has its own characteristics.
Plastering surfaces must necessarily include a reinforcement process. It is recommended to use fiberglass mesh, which does not break down in an alkaline environment.
The surface should be painted with a deep penetration primer twice.
Apply thin layer plaster about 5 millimeters thick and drown the mesh in it. After drying, apply the base coat using beacons.
Which is better plaster
If vapor permeability is required for the kitchen, bathroom or sauna, mixtures of gypsum with perlite sand are used. Silicate is also suitable, but it must be taken into account that such mixtures are incompatible with acrylic, silicone, and latex materials.
For use on aerated concrete, you can use cement-lime mixtures, which do not require priming the walls.
Set of tools
Finishing aerated concrete surfaces requires the following tools:
- Spatulas.
- Scraper to remove dirt and debris.
- Metal brushes.
- Hammer for knocking down irregularities and protruding mortar.
- Sandpaper.
- Brushes, rollers for priming.
- Master OK.
- Tank for mixing the solution.
- Mixer for preparing the solution.
- Falcon, shield where the mixture is applied.
- Grout grater.
- Poluterok.
- The rule is to align the corners.
How to plaster: progress of work
Ready-made mixtures are excellent for finishing, but have a high cost, so for do-it-yourself wall preparation technology is proposed, after which you can safely use any composition.
For preparation you will need tile adhesive, fiberglass mesh, and deep penetration primer. It is necessary to smooth out all chips and cracks with a compound for laying aerated concrete blocks, then remove dust and debris from the wall with a cheek and paint it with a deep penetration primer twice.
Tile adhesive is diluted and applied to the surface with a thickness of 5 millimeters, the mesh is pressed on top with a notched trowel. When the layer is completely dry, apply plaster in the usual way, any solution can be used.
The costs of this technology will be an order of magnitude less than when using ready-made plasters.
How long before you can move on to the next stages of wall finishing?
After completion, the beacons are removed, and the resulting dents are subsequently sealed with putty.
To move on to the next types of finishing, you must wait until the walls are completely dry at a constant temperature. Drying will require about a month in the warm season to ensure that temperature changes do not lead to cracking or peeling. It is not advisable to speed up the process; if necessary, a heater is used.
Interior and exterior finishing of a house is an important stage of construction work, the quality of which determines the durability, comfort of living and aesthetic appearance of the house. For finishing works there are many modern materials and technology, but traditional methods, do not lose popularity and are still relevant today. These methods allow you to achieve the necessary results at low cost and labor intensity.
Useful video
Low-rise construction using gas silicate blocks has become widespread in all climatic zones of our country. Unique properties materials, which we will discuss in detail below, allow the construction of aerated concrete structures in hot regions and in places where negative temperatures prevail. However, implement directly construction works- only half the battle. Comfort of further living in the house, its durability and preservation performance characteristics depend on the proper finishing of the façade and inner surface walls One of the main stages is plastering aerated concrete walls indoors. Let's take a closer look at the technology of the finishing process and the nuances that affect the quality of the final result.
Features of plaster on aerated concrete
To figure out what, when and how to properly plaster aerated concrete, you need to study the properties of the building material itself. The peculiarities of plastering walls are associated precisely with the unique characteristics of gas silicate blocks.
Initially, aerated concrete was developed as a material that was used to insulate buildings. Therefore, research was carried out in the direction of creating a porous structure, which, as is known, provides maximum thermal insulation.
As a result, two varieties emerged:
- foam concrete, the porosity of which is achieved by forced mechanical foaming;
- aerated concrete, in which gas bubbles are formed by adding aluminum chips that react with the main composition (hence the name of the material).
During the process of creating blocks, gas bubbles tend to the surface, making their way through the thickness of the mixture. Therefore, the cells in the structure of aerated concrete are not isolated, but represent a unique system of interconnected channels. This is due to main feature material, thanks to which the finishing technology for gas silicate differs significantly from other building materials. This difference is vapor permeability. Aerated concrete perfectly conducts saturated water vapor through its structure. At the same time, it has increased hygroscopicity, that is, it is able to quickly absorb moisture and retain it inside for a long time.
Based on the foregoing, the fundamental principle for plastering walls made of aerated concrete looks like this: water vapor should be able to be easily removed from the thickness of the walls or should not penetrate inside at all. Failure to comply with this approach is fraught with serious problems during the cold season: negative temperatures the moisture inside the blocks will freeze, and the material will simply “tear”: cracks will appear, shedding will begin, not only the appearance, but also the thermal insulation characteristics. To prevent this from happening, it is necessary A complex approach to the choice of options for external and internal finishing of the building.
We immediately answer the question: is it necessary to carry out external work? Definitely yes, because:
- influence of factors external environment on the porous structure of the material will lead to accelerated erosion;
- the above-mentioned structure, consisting of almost end-to-end microchannels, makes the material sufficiently blown by air currents, which creates discomfort when living in a house in cold, windy weather;
- insufficient mechanical strength open material makes it vulnerable to accidental impacts and other force impacts;
- a finished wall definitely has aesthetic advantages over untreated masonry.
Dependence of internal plaster on facade finishing
To clearly demonstrate the reasons for the need to select a material for interior work in accordance with the design option for the external surface of the walls, consider the main characteristics various types aerated concrete. For ease of perception, we will create a summary table of parameters:
From the above data it is clear that even the densest and most durable brand of aerated concrete has a high energy saving rate (the value of the thermal conductivity coefficient of 0.15 was compared with the same indicator natural wood, traditionally considered the standard warm materials). At the same time, vapor permeability remains at a significant level for all brands of gas silicate.
During human life, moisture is constantly released into the air in interior spaces. In addition to the normal breathing of the inhabitants of the house, there are business processes, including washing and drying clothes, washing dishes, and high humidity in sanitary facilities is their integral property. As mentioned above, excess moisture must either be easily removed through gas silicate walls, or not reach the surface of the material at all.
If special vapor-permeable plaster is used for exterior work, then a similar composition must be used inside. As a result, the overall vapor conductivity will remain virtually unchanged compared to the original characteristics of aerated concrete, and the aesthetic appeal and wear resistance of the structure will increase significantly.
Ventilated facades
An alternative option for exterior finishing, in which vapor-permeable plaster is also used for interior work, is the creation of ventilated facades. This technique involves installing a ventilation gap between the wall surface and the layer of finishing material. The most common examples similar options siding or trim protrudes brickwork"into the loose" The creation of ventilated facades provides for the possibility of additional external insulation of walls, however, it is also necessary to use materials with appropriate vapor permeability: mineral wool is quite acceptable, while foam plastic and extruded polystyrene boards are categorically unacceptable.
Other finishing options
Other materials for facade decoration (traditional plaster compositions, adhesive bases for decorative stone, porcelain stoneware, etc.) interfere with the vapor permeability of aerated concrete, so internal work must also ensure maximum vapor barrier. In such cases, it is advisable to use special hydrophobic primers and finishing materials based on sand and cement, and the thickness of the plaster should be significantly greater than for compositions used while maintaining the ability of the walls to transmit water vapor.
With this method of finishing, the room must have a well-thought-out ventilation system. Otherwise, constant humidity will lead to multiple manifestations of fungus and mold.
Materials
The given recommendations help solve the problem of choosing budget options for interior decoration. Which is better: plaster or drywall? The vapor conductivity coefficient of the densest aerated concrete is 0.16, and the same indicator for gypsum sheets = 0.07, which is more than two times less. Therefore, it is recommended to use plasterboard only in the case of constructing blind vapor barrier external facades; to create a ventilated structure, it is necessary to use plaster mixtures for aerated concrete surfaces inside the house.
With regard to the kitchen, bathroom and toilet in houses made of gas silicate, the question no less often arises: is it possible to lay tiles? The answer is similar: since vapor conductivity ceramic products is close to zero, such finishing is acceptable with hydrophobic design of the walls on the outside.
How to plaster aerated concrete
Having understood the features of the technology, let’s move on to choosing the finishing material itself. With today's diversity building mixtures It’s not difficult to decide what to plaster with.
Most branded manufacturers of building materials produce compounds for working on aerated concrete. The most popular plasters include AeroStone, Bonolit, Ceresit or Knauf. Vapor-permeable plasters are somewhat more expensive than conventional plasters, so when deciding which is better, the financial side plays an important role.
Before purchasing, be sure to read the product description and make sure that the mixture you are purchasing is actually intended for use on aerated concrete.
Preparing the walls
So, is it necessary to plaster - we figured it out, with suitable materials We've decided, let's get to work. Gas silicate blocks They have a standard size and are laid in perfectly even rows, so preliminary leveling of the surface requires minimal effort and time. This is usually done using grout mesh or sandpaper.
The next step is priming for plaster. This procedure cannot be skipped, because otherwise the finishing material will not adhere well to the walls or will quickly crack during use.
Plastering process
Next we move on to the finishing work itself. The technology of how to plaster aerated concrete walls indoors is not much different from similar works on any wall base and can be easily done with your own hands:
- vertical beacons are installed along the width of the rule;
- Preliminary puttying of the walls without plaster is carried out to secure the fiberglass mesh.
Is a mesh needed?
We will devote a separate section to this aspect. Plaster is a rather fragile coating. Therefore, with the slightest shrinkage of the foundation, cracks may appear on the surface, despite the monolithic reinforcing belts and other strength of the structure. Such phenomena can be avoided by laying a special mesh made of materials resistant to alkaline environments. Strong fibers reinforce the surface and prevent cracking.
Despite the additional acquisition costs, the answer to the question of whether a mesh is needed is clearly affirmative.
If you want the finish to last for a long time, do not start work immediately after construction is completed. The house needs to stand for at least 6 months, and preferably 1 – 1.5 years. This will allow the aerated concrete to achieve optimal moisture levels, and the foundation to undergo final shrinkage.
We continue the plastering process:
- spread a layer of plaster from bottom to top over the area to be treated;
- guided by the beacons, we level the surface;
- dismantle the beacons and seal their attachment points;
- After drying, we finally rub down the walls.
Tools
Scroll necessary tools small:
- sandpaper and grout mesh;
- long profiles for beacons;
- brush or roller for applying primer;
- dilution container plaster mixture;
- spatula for application;
- rule for leveling the surface
Putty
If you plan to further paint the aerated concrete, after plastering it is recommended to carry out finishing putty. This will improve the adhesion of the paint to the surface and increase its service life. To perform the operation, use special compounds for puttying aerated concrete, sold in construction supermarkets.
Aerated concrete blocks for building houses are becoming increasingly popular: they are light, smooth, and retain heat well due to their porous structure. But their high vapor permeability imposes serious restrictions on the choice of finishing materials and the technology of their use.
In particular, before plastering aerated concrete on the outside, you need to complete all “wet” internal work, select suitable composition and calculate the thickness of its application. All this will be discussed in more detail in the article.
The composition of aerated concrete is similar to ordinary concrete: it contains cement, sand, lime and water. But the addition of aluminum powder, which is a gas-forming agent, gives it a specific porous structure. Moreover, unlike foam concrete, the pores are open, which increases the vapor permeability of the material.
Open pores on the surface of building blocks cannot be left unfinished for many reasons.
For example:
- Exposure to precipitation. Wetting of the outer layer reduces the thermal insulation properties of the walls, leads to the appearance of cracks on the surface and even their destruction when exposed to temperature changes;
- Settlement of airborne dust. She, like rainwater, is acidic in nature, and prolonged exposure to an acidic environment causes darkening of the surface and leads to a deterioration in the appearance of the blocks.
That is why the instructions require mandatory external finishing of such surfaces. It can be performed different ways, including the installation of hinged ventilated facades, brick cladding with ventilation gap etc.
But most often for protective and decorative finishing special facade plaster for aerated concrete is used. Its main purpose is to protect walls from the factors listed above, but the coating should not reduce their vapor permeability, preventing the diffusion of water vapor from the inside to the outside.
Note. Decorative paint and varnish compositions must also meet the same requirement, therefore film-forming paints are not used for finishing such facades.
Specific brands of such plaster will be discussed below, but now it is necessary to emphasize this important point, as requirements for the timing of applying exterior finishing.
It should only be executed after:
- Building shrinkage;
- Completion of interior finishing associated with “wet processes”: installation of floor screed, plastering and puttying of walls, leveling of ceilings, painting, etc. The fact is that the solutions used for this contain a lot of water, which, during the drying process, evaporates and is removed, including through the pores of aerated concrete. If you block her path with a layer of external plaster, it will accumulate in the material, which will lead to the loss of its properties and peeling of the external finish.
Compositions for plastering aerated concrete
Like all other similar mixtures, facade plaster for aerated concrete is produced both on a mineral basis (see Mineral facade plaster: features of the material) and on a polymer base.
Mineral mixtures
To finish walls made of aerated concrete and gas silicate, light mineral plasters are used, to which perlite or other porous and lightweight filler is added instead of ordinary sand. This composition is light in weight, does not place a large load on the base and has increased vapor permeability.
Many manufacturers produce such plaster.
We list the most popular brands:
- Founds Startwell T-21. A cement-lime mixture suitable for both exterior and interior use. It can be applied manually or mechanically (see Machine plaster: how to do it right).
- Kreps Extra-Lite. Cement-lime mixture with fine-grained sand and special additives for machine and manual application to facades, interior walls, ceilings.
Note. When adding Kreps Antifreeze to the solution - antifreeze additive of the same brand - it can be applied at ambient temperatures down to minus 10 degrees.
- Plitonit T1 and Plitonit T. The first composition is intended for sealing joints and rough leveling of surfaces, has a maximum filler size of 2.5 mm, and is applied up to 30 mm thick. The second is a thin-layer leveling plaster with a maximum fraction of 0.63 mm and an allowable layer thickness of 10 mm.
- Baumit ArtoPlast (Austria). Thin-layer cement facade plaster on aerated concrete and cellular concrete. It is also used for attaching reinforcing fiberglass mesh to a leveled base.
- Baumit GrundPutz Leicht. Lightweight lime-cement plaster with filler that improves the thermal insulation properties of facades.
Polymer mixtures
Many compositions based on acrylic resins are suitable for plastering aerated concrete, as they have good vapor permeability. But silicone (see Silicone plaster: material features) and silicate mixtures can boast similar properties, which can also be used as a finishing material. decorative covering. The leader in their production is the Austrian company BAUMIT.
Among the most popular are the following ready-to-use formulations:
- Baumit SilikatTop is a silicate plaster with a textured or rough surface, high vapor permeability and weather resistance.
- Baumit SilikonTop is a silicone plaster with a textured or rough surface, normal vapor permeability and weather resistance. It has dirt-repellent properties and is easy to clean.
Note. The price of ready-made polymer polymer plasters is higher than mineral ones. But they can be tinted before application, eliminating the need for subsequent surface painting.
Whatever mixture you choose for exterior finishing, you must follow the following rule: the vapor permeability of the finished multi-layer “pie”, consisting of interior plaster, the wall itself and facade plaster, should increase from the inside to the outside. It is allowed to deviate only slightly from this requirement, using materials with the same vapor permeability for adjacent layers.
Technology of finishing aerated concrete with plaster
It should be noted that finishing facades made of aerated concrete, if it is performed according to all the rules, is not the fastest, easiest or cheapest operation. It consists of several stages.
Primer
Before applying a primer to the surface, it is necessary to seal all seams and cracks, and clean the surface of the walls from dust and dirt. It must be dry, and work must be performed at an ambient temperature of 10-25 degrees above zero.
The main purpose of the primer is to strengthen the base and protect it from moisture. Therefore, it must be suitable for use on loose and porous surfaces. Before purchasing, carefully study its composition, properties and purpose, information about which is indicated on the packaging.
As a rule, water-repellent compounds based on acrylate siloxane are used to work on aerated concrete.
Reinforcement
In order for the plaster to adhere well to the surface, a reinforcing layer is required (see Reinforcing mesh for plaster: how to use), which is an alkali-resistant fiberglass mesh. Resistance to alkali is a mandatory requirement for this material, since the plaster solution can completely destroy it over time, which will lead to cracks and peeling of the coating. Therefore, it is not worth saving on the mesh.
It is attached to the base either with self-tapping screws or glued to a freshly applied layer of plaster. When insulation and plastering of the façade of a house made of aerated concrete is carried out, the mesh is glued over the insulation layer.
Plaster
External plaster for aerated concrete is applied over a grid in the usual way. The thickness of the layer depends on the condition of the surface and the size of the aggregate fraction. The recommended thickness is also indicated by the manufacturer on the packaging.
There are other ways facade finishing aerated concrete blocks. For example, if the walls are neatly built from even blocks, it is enough to float them, rub the seams, fill small potholes and treat them with vapor-permeable putty. It is diluted to a creamy consistency and applied to the surface using a roller or wide brush.
Can be entered in ready solution water-based color, then the facades will not have to be painted. But it is advisable to repeat this treatment twice, allowing the first layer to dry before applying the second.
Conclusion
Having decided to plaster a house built of aerated concrete, you need to carefully select materials. Only if all the recommendations listed above are followed, such finishing will not deteriorate the properties of the walls and will last a long time.
As for the technology of applying plaster, it is described in detail in the video in this article. Study it carefully before taking on this difficult task.
Houses made of aerated concrete are popular due to their ease of construction and the relatively low price of aerated concrete blocks. However, the lightweight porous material is defenseless against moisture, frost and strong winds. One of available ways protection is aerated concrete plaster. Information about how plastering is carried out inside and plastering the facade will be useful not only for those who recently installed aerated block walls under the roof, but also for those who have undertaken repairs.
Features of aerated concrete
To know which mixtures to choose for plastering walls made of aerated concrete blocks, you need to study the features of this material. They are determined by production technology. There are two ways to obtain porous artificial stone - autoclave and natural hardening (hydration or non-autoclave).
The differences are:
- color (hydration – pronounced gray);
- geometric accuracy (autoclave is more accurate);
- strength (autoclave has higher indicators);
- density, thermal conductivity (the optimal ratio of indicators for autoclave);
- fragility (hydration leads);
- durability (autoclave is in the lead).
When making aerated concrete, lime, quartz sand, cement, a gas-forming reagent (usually aluminum paste or powder) and water are mixed. When mixing the solution, lime reacts with aluminum, releasing hydrogen. Gas, released throughout the entire volume, forms numerous small pores. And since light hydrogen tends to escape, passages appear between the pores.
Thus, the aerated concrete structure is dotted with small pores, between which air channels pass. Because of them, the material has increased water and vapor permeability.
Regardless of the method used to obtain the porous material, its disadvantages are:
- high water absorption;
- the ability to cause corrosion of metal fasteners;
- poor adhesion;
- unaesthetic appearance;
- breathability (through channels, which retain heat in calm conditions, lose their thermal insulation properties in windy weather);
- rapid destruction in the absence of a protective finish.
Therefore, aerated concrete especially needs to be coated with materials suitable for it.
Applied methods of protection:
- ventilated facade (porcelain tiles, lining, siding, etc.);
- "wet facade";
- protective coloring;
- brick cladding;
- plastering.
When choosing plaster protection, you should know which of the existing finishing materials is better.
Basic requirements for plaster
The compositions used indoors for protective plastering of aerated concrete walls should help create a healthy microclimate. Facade plaster for aerated concrete must also be weather-resistant and able to withstand temperature changes (resistance to low temperatures), reduced water permeability.
Aerated concrete plaster must have the following properties (regardless of the place of application):
- reliable adhesion to aerated concrete surfaces (≥0.5 MPa);
- vapor permeability;
- strength;
- water requirement no more than 200 ml per 1 kg of dry mix (dry mixture);
- fire resistance;
- environmental friendliness;
- biostability;
- durability;
- decorativeness.
Which plaster is better for plastering aerated concrete walls?
Taking into account the above requirements, plaster compositions have been developed specifically for aerated concrete blocks.
They are divided into:
- mixtures for interior work;
- compositions for universal use;
- facade plaster.
Of the indicated compositions, aerated concrete plaster for external use is the most resistant in all respects, as it is used in the most unfavorable conditions.
According to their intended purpose, the compositions are:
- ordinary (for leveling - rough finishing);
- special (perform additional functions, for example, etc.);
By type of binder:
- and etc.
For beginners, information about the shelf life of the solution is important. Short term requires quick plastering before the solution begins to set.
Liquid glass is used as a binder for silicate plaster. This is a durable material with such advantages as:
- vapor permeability;
- durability;
- resistance to aggressive substances in a polluted atmosphere;
- strength;
- non-susceptibility to biodestruction;
- resistance to long-term exposure to UV rays;
- fire safety;
- strong adhesion to the base;
- non-shrinkage during hardening;
- easy cleaning (dirt is washed off by rain or watering from a hose).
Silicate coating perfectly protects porous and “soft” materials.
- it requires primers (as well as paints and varnishes) on a related basis;
- this product is not cheap;
- poor palette of ready-made mixtures;
- requires skill, as the shelf life is limited (problematic for beginners);
- under the influence of precipitation, the coating darkens and temporarily becomes spotted;
- work clothes are not cleaned after plastering work.
They are practically not used for interior decoration. They produce ready-made and dry mixtures.
Incompatible with finishing materials based on latex, silicone, acrylic.
A relatively new binder, silicone, is successfully used in plastering compositions in the form of silicone resins. The only significant drawback is the high price.
Forms coatings:
- vapor permeable;
- very durable;
- durable;
- highly elastic (no cracks form even when cracks form in the walls);
- firmly adheres to any surface (except for metal bases);
- resistant to chemicals;
- are not affected by biological organisms;
- maintaining strength and appearance at high temperatures;
- with unlimited layer thickness;
- do not collect static;
- easy to clean;
- hydrophobic.
It is universal in application.
Acrylic plaster of aerated concrete
It gained popularity due to its attractive combination of price and quality. Created on the basis of acrylic derivatives - acrylic resins.
- elastic;
- durable;
- environmentally friendly;
- waterproof;
- easy to stack;
- durable;
- features a rich palette;
- not susceptible to fungi, rot, mold;
- washed with a hose.
- accumulates static;
- low vapor permeability;
- not resistant to flame;
To level out the disadvantages, additives are used. However, these mixtures are not used in bedrooms and living rooms.
Cement-sand
We immediately reject the idea of using conventional cement compositions. For example, standard (CPS) ones are too dense and heavy for fragile aerated concrete; due to low adhesion, cracks on the surface are inevitable.
The most important reason why you cannot plaster CFB is the vapor permeability of CFB; it is lower than that of cellular concrete. Creating an optimal microclimate for living becomes impossible.
Leading companies have modified cement mixture, making CPS suitable for porous substrates with the help of additives.
Lime-cement
Low vapor permeability and poor adhesion of cement compositions to aerated concrete are eliminated by adding lime to them. You can prepare such compositions yourself, this will save your budget.
- hardens quickly, gaining strength;
- non-shrinking, cracks do not appear during hardening;
- has vapor permeability;
- plastic, easy to fit, keeps its shape;
- adheres firmly to aerated concrete;
- does not give up its water to the porous base;
- environmentally friendly;
- fireproof;
- forms coatings with low weight;
- repairable;
- easy to sand;
- capable of forming a smooth surface.
- "rabies";
- low frost resistance;
- short lifespan.
Of all the compositions, this is the best for plastering aerated concrete surfaces of residential premises. Since aerated concrete walls and partitions, as a rule, have a flat surface, the plaster coating can be made to the minimum possible thickness. For gypsum mixtures this is 1 mm. In the case of cement mortars - 10 mm.
Gypsum compositions with perlite sand are perfect for insulating gas blocks.
Most popular manufacturers
Plaster mixtures for finishing aerated concrete are available in the product lines of all major plastering manufacturers. Mixtures of popular brands are distinguished by exact correspondence of qualities to the declared indicators.
Among the popular manufacturers are the following companies:
- German concern Henkel (develops and produces plasters under the Ceresit brand);
- Austrian brand Baumit;
- the Knauf company, which initially produced gypsum mixtures, also produces cement-based mixtures;
- Krasland company;
- Bolars (Uniplast mixture);
- A number of plasters for aerated concrete are produced by the Pobedit company.
From the Ceresit line, the brands CT 24 and ST 77 and others are most often used for aerated concrete. ST 24 is a lightweight cementitious, frost-resistant, vapor-permeable plaster mixture for leveling for universal use. ST 77 – acrylic aerated concrete façade plaster, ST 35 – decorative mixture"bark beetle" for facade use.
Popular in the Baumit line are the cement-lime composition Baumit HandPutz for universal use, the silicone composition SilikonTop, the silicate mixture SilikatTop, and the acrylic Nanopor Top.
From Knauf mixtures for aerated concrete walls suitable gypsum Knauf-Profi, gypsum polymer Eisberg, gypsum with polymer additives Rotband, Goldband, cement Grunband (thermal insulation), Sevener.
The Krasland company produces compositions specifically for aerated concrete walls, for example, Aerated Concrete-2.
Features of plastering
Aerated concrete blocks are brought to the construction site immediately after production, when they are still full of moisture that has not evaporated (up to 30%). During the installation process, water from the masonry mortar and sediment enters the blocks. Therefore, the walls of a newly erected structure are filled with moisture. To dry out, they need to stand under the roof for at least six months. Aerated concrete also shrinks in the first year.
Therefore, the new building is not plastered. You also cannot plaster aerated concrete inside and outside the house at the same time (you need to give the walls time to dry).
Aerated concrete walls are first plastered indoors, and after a few months - along the facade.
General diagram of a multi-layer “pie” of plastered walls: least vapor permeable - interior coverings, the most vapor-permeable are external coatings.
In regions with a damp climate, do not wait until next season for plastering. Highly plastic compositions with high vapor conductivity are used.
The vapor conductivity of the plaster coating on the outside of the building should be higher than that of the interior finishing.
How and with what to plaster aerated concrete inside a house
It is easier to select a composition for internal plastering of aerated concrete walls than for external plastering, since the choice of mixtures is wider. The compositions are suitable not only for internal plastering, but also mixtures for external work. In addition, it is possible to use gypsum compounds indoors. The use of compositions with vapor permeability lower than that of aerated concrete is encouraged. In damp rooms, denser compounds or waterproofing mixtures are used.
There are some selection problems. They occur if the facade has been insulated with expanded polystyrene or polystyrene foam (without a ventilation gap). These materials are practically vapor-tight; removal of moisture from aerated concrete walls into the room is also unacceptable. Read more about or read our articles.
Since moisture accumulates inside the wall, access to aerated concrete is blocked by using indoor plaster compositions with vapor permeability much lower than that of aerated concrete blocks. That is, cement, dense plaster. In this case, the role increases ventilation system in lead humid air from the premises.
Suitable for facades: silicate, cement-lime, silicone mixtures; for premises - cement-lime, gypsum-perlite, gypsum-lime compositions.
If plastering inside is carried out first, then in addition to choosing plasters suitable for aerated concrete, measures are taken to prepare a base that has very low adhesion and the ability to absorb water easily and in large quantities. The walls must be treated with deep penetration primers, following the manufacturer's instructions. Even small excesses of water should not be allowed in the primer and plaster compositions.
To cope with low adhesion, when plastering aerated concrete walls indoors, apply a rough plaster layer (at least 0.5 cm) and use fiberglass or polyurethane reinforcement.
How and with what to plaster aerated concrete outside the house
When deciding the best way to plaster aerated concrete on the outside, they rely on the rule that the vapor permeability of the outer material should be equal to or greater than that of aerated concrete. The compositions must be intended for facades or universal. Outside the house, the loads and impacts on the surface of the structure are higher. Therefore, it is impossible to do without reinforcement.
For the outside of the building, it is better to use mineral wool, heat-insulating plaster or plasterboard for insulation.
A year after applying the finishing layer, it is coated with a water-repellent composition, which gives the surface water-repellent properties.
Optimal conditions for applying plaster
To obtain a plaster coating with the necessary qualities, it is necessary to comply with a number of conditions, including the conditions under which plastering is carried out. For plastering aerated concrete walls during interior work, the temperature range is from +5 to +30°C. Drafts and humidity above 60% are not allowed in the room. It is more rational to predict the start of plastering by the end of the heating season.
For external plaster on aerated concrete, choose a time when the temperature does not fall below +8°C for several days. Do not plaster the façade when the humidity is more than 80%, possible frost, or in windy or hot weather. The place of finishing work is protected from the sun and precipitation.
If the season ends and it is not possible to plaster the facade, then it is coated with a primer (use a deeply penetrating agent) in two passes and left until spring. Additionally, the walls are sometimes covered with film for the winter.
Technology for plastering aerated concrete facades
How to plaster walls made of aerated concrete blocks?
For aerated concrete walls and partitions, two methods of applying solutions are used:
- thick-layer (the solution is applied in one layer and then rubbed);
- thin-layer (the mixture is applied in several passes).
The general step-by-step picture of plastering is as follows:
- The base is being prepared.
- Apply primer.
- Prepare a solution or prepare a ready-made mixture.
- The first layer is applied, reinforced, treated with a notched trowel, and dried.
- A second layer is applied, leveling the comb of the first. Dry.
- Apply the third (smoothing) layer. Rubbed out. Dry. Grinding. The layer is performed if necessary for finishing, for example, coloring.
Surface preparation
The precision with which aerated concrete blocks are made allows builders to make fairly even masonry. Such walls need preliminary preparation. Typically, blocks are placed on adhesive composition. At the same time, the blocks do not become damp as much as when laid on mortar, and the walls dry faster.
During preparation, if the adhesive solution protrudes from the plane of the wall, it is planed with a float designed for aerated concrete or a plane. You can also cut off some of the protrusions. If there are chips or cracks, they are filled with an adhesive composition, to which dust generated when cutting blocks can be added. Having filled the depressions with a narrow spatula, remove all excess and dry the adhesive composition. After this, the surface is rubbed.
The preparation of aerated concrete for plaster is completed by sweeping away the dust.
Padding
A little about how you can prime aerated concrete before plastering.
Of the compositions, the most popular are deeply penetrating Knauf Grundiermittel, Aerated concrete-contact-1, Siltek E-110. Acrylosiloxane primer for aerated concrete makes the surface of the blocks waterproof. A layer of primer is applied with a roller or brush in two or three passes and allowed to dry. In areas with a dry climate, one layer may be sufficient; in areas with a humid climate, 3 layers are applied.
Do not dilute the primer with water!
Aerated concrete plaster and reinforcement
Beginners are interested in whether a grid is needed. If the solution is applied in one layer up to 10 mm, then with a high-quality primer in the room, reinforcement is dispensed with. However, for façade coverings, mesh is an additional strength that cannot be avoided.
A fiberglass mesh (alkali-resistant!) with 3x3 mm mesh is placed on a freshly laid layer of mortar (at least 5 mm) and embedded into it with a spatula. The panels are overlapped by 5 cm. The layer with the mesh is formed with a notched trowel, creating horizontal stripes-ribs, then dried.
If the coating thickness is ≥7 mm, beacons are used. When working outdoors, two more layers are applied: the second is leveling, the third is to form a durable, smooth surface. The latter is rubbed down with sandpaper or an abrasive mesh.
Finishing layer
To decorate walls, decoration with plaster, painting or wallpaper is most often used. These materials must be vapor permeable. The surface of the dried plaster coating is primed before applying the finishing finish. Wall plastering technology decorative compositions set out in section.
Insulation of aerated concrete walls
Temperature changes, as well as sub-zero temperatures, are harmful to aerated concrete. Strength decreases and the structure collapses. Basically, insulation of aerated concrete walls is done outside the structure. Used as insulation mineral wool. And since this material is soft, plastering over it is impossible.
Plastering walls made of aerated blocks is performed only to level the surface for a tight fit of the mineral wool to the wall. In order to lay and attach the insulation, a metal casting is mounted on the wall and wooden blocks(the distance is 2 cm less than the width of the mineral wool sheet). The canvas is attached to the wall with adhesive foam or glue and umbrella dowels are used.
A vapor barrier film is placed on top of the insulation, which is attached to brackets to the bars and covered with an adhesive solution. Perforated corners with mesh are installed in the corners. Then the ventilation façade is installed.
When insulating with mineral wool, acrylic mixtures are not used.
If insulation of external walls is not possible, insulation is carried out indoors using warm plaster or gypsum plasterboard (plasterboard sheets).
In presenting the material on plastering aerated concrete walls, we tried to answer FAQ newcomers – owners of a private house. Now you have an idea which aerated concrete plaster is best, how to properly plan plastering, how to plaster block house inside or outside.
A house made from a material such as aerated concrete has many differences from houses built using foam concrete or brick. Aerated concrete is lightweight artificial stone, which has a porous structure and high thermal insulation properties, which indicates that the plaster used for aerated concrete is not ordinary.
So what kind of plaster should be used for exterior decoration houses made of aerated concrete blocks? What kind of solution should this be, and why can’t you use regular mixtures?
As you may have guessed, to perform external wall protection, use ordinary cement-sand plaster mortar it is forbidden. The reason for this ban is that ordinary plaster lower vapor protection parameters than the aerated concrete blocks that make up the building.
There is an unspoken principle that any multi-layer breathable wall structure must be built using such a method that each subsequent layer has greater vapor permeability than the previous one. The closer to the street, the greater the permeability.
As an exception, it is possible for all layers to have this indicator of the same level, but this is not encouraged.
For work with aerated concrete blocks You should use exclusively special facade plaster for aerated concrete, which is called that.
How to plaster aerated concrete
Plastering walls made of aerated concrete is done as follows: apply facade plaster for aerated concrete blocks to the walls. This material is a special porous plaster mixture that has high vapor-permeable properties.
It is advisable to apply the plaster on the mesh so that it does not crack or fall off when it dries.
Plaster, which is used for finishing buildings made of aerated concrete, must have the following necessary qualities:
- bulk weight – about 0.8 kg/dm³;
- fraction within 2 – 4 mm;
- it should be a light plaster mortar belonging to plasters of group P I;
- resistance to compression pressure – class CS I;
- low water absorption coefficient;
- non-flammability - class A1.
The plaster mixture used to finish the façade of aerated concrete houses must have good ductility, it must be easy to process and should be applied on top of the base. This plaster can be applied in a layer whose thickness does not exceed 1.5 cm at a time.
Once hardened, this plaster should have good water-repellent properties.
However, nevertheless, it must have a good throughput with respect to water vapor, and in addition, it must easily cope with the harmful effects of adverse weather conditions.
How to plaster aerated concrete video
It’s worth saying right away that plastering work on aerated concrete are neither simple nor cheap.
If you have already firmly decided to carry out plastering work in a house made of aerated concrete, then use only suitable materials for this. Don’t forget, this is the guarantee that the work you perform will be of high quality, and the plaster will delight your eye for many years.
